Fixed #21951 -- Updated docs to use __str__ for Python 3

Thanks Tim Graham for the report and recommendations

docs/ref/contrib/admin/actions.txt

@@ -57,8 +57,7 @@ simple news application with an ``Article`` model::
         body = models.TextField()
         status = models.CharField(max_length=1, choices=STATUS_CHOICES)
 
-        # On Python 3: def __str__(self):
-        def __unicode__(self):
+        def __str__(self):              # __unicode__ on Python 2
             return self.title
 
 A common task we might perform with a model like this is to update an

docs/ref/contrib/admin/index.txt

@@ -512,7 +512,7 @@ subclass::
         list_display = ('first_name', 'last_name')
 
     If you don't set ``list_display``, the admin site will display a single
-    column that displays the ``__unicode__()`` (``__str__()`` on Python 3)
+    column that displays the ``__str__()`` (``__unicode__()`` on Python 2)
     representation of each object.
 
     You have four possible values that can be used in ``list_display``:
@@ -563,7 +563,7 @@ subclass::
     A few special cases to note about ``list_display``:
 
     * If the field is a ``ForeignKey``, Django will display the
-      ``__unicode__()`` (``__str__()`` on Python 3) of the related object.
+      ``__str__()`` (``__unicode__()`` on Python 2) of the related object.
 
     * ``ManyToManyField`` fields aren't supported, because that would
       entail executing a separate SQL statement for each row in the table.
@@ -626,11 +626,11 @@ subclass::
               list_display = ('name', 'born_in_fifties')
 
 
-    * The ``__str__()`` and ``__unicode__()`` methods are just as valid in
-      ``list_display`` as any other model method, so it's perfectly OK to
-      do this::
+    * The ``__str__()`` (``__unicode__()`` on Python 2) method is just
+      as valid in ``list_display`` as any other model method, so it's
+      perfectly OK to do this::
 
-          list_display = ('__unicode__', 'some_other_field')
+          list_display = ('__str__', 'some_other_field')
 
     * Usually, elements of ``list_display`` that aren't actual database
       fields can't be used in sorting (because Django does all the sorting

docs/ref/contrib/contenttypes.txt

@@ -259,8 +259,7 @@ A simple example is a tagging system, which might look like this::
         object_id = models.PositiveIntegerField()
         content_object = GenericForeignKey('content_type', 'object_id')
 
-        # On Python 3: def __str__(self):
-        def __unicode__(self):
+        def __str__(self):              # __unicode__ on Python 2
             return self.tag
 
 A normal :class:`~django.db.models.ForeignKey` can only "point

docs/ref/contrib/gis/commands.txt

@@ -65,7 +65,7 @@ of using ``ogrinspect`` :ref:`in the tutorial <ogrinspect-intro>`.
 
 .. django-admin-option:: --name-field <name_field>
 
-   Generates a ``__unicode__`` routine (``__str__`` on Python 3) on the model
+   Generates a ``__str__`` routine (``__unicode__`` on Python 2) on the model
    that will return the given field name.
 
 .. django-admin-option:: --no-imports

docs/ref/contrib/gis/layermapping.txt

@@ -61,8 +61,7 @@ Example
         poly = models.PolygonField(srid=4269) # we want our model in a different SRID
         objects = models.GeoManager()
 
-        # On Python 3: def __str__(self):
-        def __unicode__(self):
+        def __str__(self):              # __unicode__ on Python 2
             return 'Name: %s' % self.name
 
 3. Use :class:`LayerMapping` to extract all the features and place them in the

docs/ref/contrib/gis/tutorial.txt

@@ -244,8 +244,7 @@ model to represent this data::
         objects = models.GeoManager()
 
         # Returns the string representation of the model.
-        # On Python 3: def __str__(self):
-        def __unicode__(self):
+        def __str__(self):              # __unicode__ on Python 2
             return self.name
 
 Please note two important things: